Update style and fix PR comments

Signed-off-by: Peter Nied <petern@amazon.com>

server/src/main/java/org/opensearch/identity/AccessToken.java

@@ -1,22 +1,27 @@
-package org.opensearch.identity;
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
 
-import org.joda.time.DateTime;
-import org.opensearch.common.io.stream.NamedWriteable;
+package org.opensearch.identity;
 
 /**
  * Tamperproof encapsulation the identity of a subject
- * 
+ *
  * @opensearch.experimental
  */
 public class AccessToken implements AuthenticationToken {
 
     /** Actual implementation would be something like:
-    
+
     public String accessToken;
     public DateTime accessTokenExpiration;
     public String refreshToken;
-    public DateTime refreshTokenExpiration; 
-    
+    public DateTime refreshTokenExpiration;
+
       */
 
 }

server/src/main/java/org/opensearch/identity/AccessTokenManager.java

@@ -1,8 +1,16 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
 package org.opensearch.identity;
 
 /**
- * Vends out access tokens 
- * 
+ * Vends out access tokens
+ *
  * @opensearch.experimental
  */
 public interface AccessTokenManager {

server/src/main/java/org/opensearch/identity/AuthenticationManager.java

@@ -12,7 +12,7 @@
  * Authentication management for OpenSearch.
  *
  * Retrieve the current subject or switch to a subject
- * 
+ *
  * @opensearch.experimental
  * */
 public interface AuthenticationManager {
@@ -23,7 +23,7 @@ public interface AuthenticationManager {
     public Subject getSubject();
 
     /**
-     * Get an access token manager 
+     * Get an access token manager
      * */
     public AccessTokenManager getAccessTokenManager();
 }

server/src/main/java/org/opensearch/identity/AuthenticationToken.java

@@ -1,10 +1,18 @@
-package org.opensearch.identity
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.identity;
 
 /**
  * Generic interface for all token formats to support to authenticate user, such as UserName/Password tokens, Access tokens, and more.
- * 
+ *
  * @opensearch.experimental
  */
 public interface AuthenticationToken {
-    
+
 }

server/src/main/java/org/opensearch/identity/Identity.java

@@ -10,7 +10,7 @@
 
 /**
  * Application wide access for identity systems
- * 
+ *
  * @opensearch.experimental
  */
 public final class Identity {

server/src/main/java/org/opensearch/identity/Principals.java

@@ -12,7 +12,7 @@
 
 /**
  * Available OpenSearch internal principals
- * 
+ *
  * @opensearch.experimental
  */
 public enum Principals {

server/src/main/java/org/opensearch/identity/StringPrincipal.java

@@ -13,7 +13,7 @@
 
 /**
  * Create a principal from a string
- * 
+ *
  * @opensearch.experimental
  */
 class StringPrincipal implements Principal {

server/src/main/java/org/opensearch/identity/Subject.java

@@ -14,7 +14,7 @@
  * An individual, process, or device that causes information to flow among objects or change to the system state.
  *
  * Used to authorize activities inside of the OpenSearch ecosystem.
- * 
+ *
  * @opensearch.experimental
  */
 public interface Subject {
@@ -26,7 +26,7 @@ public interface Subject {
 
     /**
      * Authentications from a token
-     * throws UnsupportedAuthenticationMethod 
+     * throws UnsupportedAuthenticationMethod
      * throws InvalidAuthenticationToken
      * throws SubjectNotFound
      * throws SubjectDisabled

server/src/main/java/org/opensearch/identity/noop/NoopAccessTokenManager.java

@@ -1,3 +1,10 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
 package org.opensearch.identity.noop;
 
 import org.opensearch.identity.AccessToken;
@@ -26,5 +33,5 @@ public AccessToken generate() {
     public AccessToken refresh(final AccessToken token) {
         return new AccessToken();
     }
-    
+
 }

server/src/main/java/org/opensearch/identity/noop/NoopAuthenticationManager.java

@@ -8,15 +8,15 @@
 
 package org.opensearch.identity.noop;
 
-import org.opensearch.identity.AccessTokenVendor;
+import org.opensearch.identity.AccessTokenManager;
 import org.opensearch.identity.AuthenticationManager;
 import org.opensearch.identity.Subject;
 
 /**
  * Implementation of authentication manager that does not enforce authentication
  *
  * This class and related classes in this package will not return nulls or fail permissions checks
- * 
+ *
  * @opensearch.internal
  */
 public class NoopAuthenticationManager implements AuthenticationManager {
@@ -27,7 +27,7 @@ public Subject getSubject() {
     }
 
     @Override
-    public AccessTokenVendor getAccessTokenVender() {
+    public AccessTokenManager getAccessTokenManager() {
         return null;
     }
 }

server/src/main/java/org/opensearch/identity/noop/NoopSubject.java

@@ -12,7 +12,6 @@
 import java.util.Objects;
 
 import org.opensearch.identity.Subject;
-import org.opensearch.identity.AccessToken;
 import org.opensearch.identity.AuthenticationToken;
 import org.opensearch.identity.Principals;